The downside of iPhone battery cases is that they're fat and make your trim device a lot bigger. The downside of slim cases is that they don't help your battery life. The Boost Case gives you the option of both: a battery when you want it and a slim case when you don't.

The case works like any other: you slip it on and your iPhone's protected. The awesome part comes when you want to add an additional 1900 mAh you can just lock it on to the back of the case. This way you can have your added battery life when you need it but leave the battery at home when you don't.